Scientists map complete neural connections in male fruit fly brain

Researchers have successfully mapped the entire central nervous system of the male fruit fly at a cellular scale. The study, conducted by the University of Cambridge and the Janelia Research Campus of the Howard Hughes Medical Institute, utilized artificial intelligence to reconstruct a three-dimensional map from millions of electron microscopy images.

The resulting map contains over 166,000 neurons and approximately 125 million synaptic connections. By comparing this data to a previously completed female brain map, scientists discovered that while 95% of the neural cells are common to both sexes, a critical 5% difference drives distinct behaviors.

These micro-level circuit variations control specific male behaviors, including aggressive fighting reflexes, the ability to track moving females through specialized visual circuits, and the production of mating songs via wing vibrations. This research provides the first concrete evidence of how specific genes physically wire the brain to direct behavioral patterns.